1. Field of the Invention
The present invention relates to an adhesion type (contact type) area sensor having an image sensor function. In particular, the present invention relates to an adhesion type area sensor having an EL element as a light source and structured by a plurality of thin film transistors arranged in a matrix shape. The EL element called a light emitting element or a light emitting diode or an OLED (Organic Light Emission Diode) includes triplet-based light emission element and/or singlet-based light emission element, for example. Further, the present invention relates to a display device combined with an adhesion type area sensor.
2. Description of the Related Art
Solid state imaging devices having a photoelectric conversion element such as a diode or a CCD for outputting an electric signal having image information from an optical signal having information such as characters and drawings on a page, and picture information have come to be used in recent years. The solid state imaging devices are used in devices such as scanners and digital cameras.
There are line sensors and area sensors in solid state imaging devices having a photoelectric conversion element. A line sensor takes in an image as an electrical signal by scanning photoelectric conversion elements formed in a linear shape over a subject.
In contrast, an area sensor, also referred to as an adhesion type area sensor, has photoelectric conversion elements formed in a plane and arranged above a subject, and takes in an image as an electrical signal. It is not necessary to scan the photoelectric conversion elements with the area sensor, differing from the linear sensor, and therefore components such as a motor for scanning are unnecessary.
FIGS. 24A and 24B show a structure of a conventional area sensor. Shown in FIG. 24A is a perspective view of the area sensor, while a cross sectional diagram of the area sensor is shown in FIG. 24B. A sensor substrate 2501 on which a photoelectric conversion element is formed, a backlight 2502, and a light scattering plate 2503 are formed as shown in the figures.
Light from the backlight 2502 as a light source is refracted within the light scattering plate 2503, and is irradiated to a subject 2504. The irradiated light is reflected by the subject 2504, and is irradiated on a photoelectric conversion element formed on the sensor substrate 2501. An electric current of a size corresponding to the brightness of the light is generated within the photoelectric conversion element when the light is irradiated to the photoelectric conversion element, and image information from the subject 2504 is taken in as an electrical signal within the area sensor.
If the light from the backlight 2502 is not irradiated uniformly to the subject 2504 with the area sensor stated above, an irregularity develops in which the read in image becomes partially brighter and partially darker. It therefore becomes necessary to devise a structure of the light scattering plate 2503 is so that the light is irradiated uniformly to the subject 2504, and to precisely regulate the position of the backlight 2502, the light scattering plate 2503, the sensor substrate 2501, and the subject 2504.
Furthermore, suppression of the size of the backlight 2502 and the size of the light scattering plate 2503 is difficult, and therefore making the area sensor itself smaller, thinner, and lighter is impeded.
In view of the above stated conditions, an object of the present invention is to provide an adhesion type area sensor which is small in size, thin, and lightweight, and in which irregularities in brightness of a read in image do not develop.
The area sensor of the present invention uses a photodiode as a photoelectric conversion element. Further, an EL (electroluminescence) element is used as a light source.
The photodiode herein has a cathode, an anode, and a photoelectric conversion layer formed between the cathode and the anode. An electric current develops due to the photovoltaic effect when light is irradiated to the photoelectric conversion layer.
Further, the EL element is a self-light emitting type element, and is mainly used in an EL display. The EL display is also referred to as an organic EL display (OELD) or an organic light emitting diode (OLED).
The EL element has a structure in which a layer containing an organic compound (hereafter referred to as an EL layer) is sandwiched between a pair of electrodes (an anode and a cathode), and the EL layer normally has a lamination structure. Typically, the lamination structure of a hole transporting layer/light emitting layer/electron transporting layer, proposed by Tang, et al., of Eastman Kodak Co. is used. This structure has extremely high light emitting efficiency, and nearly all research and development into EL displays at present employs this structure.
Electroluminescence generated by the application of an electric field is obtained in the EL element, which has an anode layer, an EL layer, and a cathode layer. There is emission of light in luminescence of the organic compound when returning to a base state from a singlet excitation state (fluorescence), and when returning to a base state from a triplet excitation state (phosphorescence), and the area sensor of the present invention may use both types of light emission.
Furthermore, a structure in which a hole injecting layer, a hole transporting layer, a light emitting layer, and an electron transporting layer are laminated in order on an electrode; and a structure in which a hole injecting layer, a hole transporting layer, a light emitting layer, an electron transporting layer, and an electron injecting layer are laminated in order on an electrode may also be used. Doping of a material such as a fluorescent pigment into the light emitting layer may also be performed.
All layers formed between one pair of electrodes are referred to generically as an EL layer within this specification. Therefore, the above stated hole injecting layer, hole transporting layer, light emitting layer, electron transporting layer, and electron injecting layer are all contained within the EL layer.
Photodiodes and EL elements are formed in a matrix shape on the same sensor substrate. The operation of the photodiodes and the EL elements is then controlled using thin film transistors (TFTs) formed on the substrate in the same matrix shape.
Light emitted from the EL elements is reflected by a subject and irradiated to the photodiodes. An electric current is generated in accordance with the light irradiated to the photodiodes, and an electrical signal having image information of the subject (image signal) is input to the area sensor.
No irregularities in the brightness of the read in image develop with the present invention because light is irradiated uniformly to the subject in accordance with the above structure. It is not necessary to form the backlight and the light scattering plate separately from the sensor substrate, and therefore it is also not necessary to precisely regulate the position of the backlight, the light scattering plate, the sensor substrate, and the subject, differing from the conventional example. A miniaturized, thin, light area sensor can therefore be realized. Furthermore, the mechanical strength of the area sensor itself is increased.
With the area sensor of the present invention it is possible to display an image by the area sensor using the EL elements. The EL elements in the present invention possess a combination of a function as a light source when reading in an image, and a function as a light source for displaying an image. Display of an image is therefore possible without forming a separate electronic display in the area sensor.
Structures of the present invention are shown below.
According to the present invention there is provided:
an adhesion type area sensor comprising a sensor portion, having a plurality of pixels, formed on a sensor substrate, characterized in that:
the plurality of pixels have a photodiode, an EL element, and a plurality of thin film transistors.
According to the present invention there is provided:
an adhesion type area sensor comprising a sensor portion, having a plurality of pixels, formed on a sensor substrate, characterized in that:
the plurality of pixels have a photodiode, an EL element, a switching TFT, an EL driver TFT, a reset TFT, a buffer TFT, and a selection TFT;
the switching TFT and the EL driver TFT control light emitted from the EL element;
the light emitted from the EL element is reflected by a subject and irradiated to the photodiode; and
the photodiode, the reset TFT, the buffer TFT, and the selection TFT generate an image signal from the light irradiated to the photodiode.
According to the present invention there is provided:
an adhesion type area sensor comprising a sensor portion, having a plurality of pixels, formed on a sensor substrate, characterized in that:
the plurality of pixels have a photodiode, an EL element, a switching TFT, an EL driver TFT, a reset TFT, a buffer TFT, a selection TFT; a source signal line; a gate signal line; an electric power source supply line for maintaining a constant electric potential; a reset gate signal line; a sensor gate signal line; a sensor output wiring connected to a constant electric current power supply; and a sensor electric power source line for maintaining a constant electric potential;
a gate electrode of the switching TFT is connected to the gate signal line;
one of a source region and a drain region of the switching TFT is connected to the source signal line, and the other is connected to a gate electrode of the EL driver TFT;
one of a source region and a drain region of the EL driver TFT is connected to the electric power source supply line, and the other is connected to the EL element;
a source region of the reset TFT is connected to the sensor electric power source line;
a drain region of the reset TFT is connected to a gate electrode of the buffer TFT and to the photodiode;
a drain region of the buffer TFT is connected to the sensor electric power source line;
one of a source region and a drain region of the selection TFT is connected to the sensor output wiring, and the other is connected to a source region of the buffer TFT;
a gate electrode of the selection TFT is connected to the sensor gate signal line;
light emitted from the EL element is reflected by a subject and irradiated to the photodiode; and
an image signal generated from the light irradiated to the photodiode is input to the sensor output wiring.
According to the present invention there is provided:
an adhesion type area sensor comprising a sensor portion, having a plurality of pixels, formed on a substrate, characterized in that:
the plurality of pixels have a photodiode, an EL element, a switching TFT, an EL driver TFT, a reset TFT, a buffer TFT, a selection TFT; a source signal line; a gate signal line; an electric power source supply line for maintaining a constant electric potential; a reset gate signal line; a sensor gate signal line; a sensor output wiring connected to a constant electric current power supply; and a sensor electric power source line for maintaining a constant electric potential;
a gate electrode of the switching TFT is connected to the gate signal line;
one of a source region and a drain region of the switching TFT is connected to the source signal line, and the other is connected to a gate electrode of the EL driver TFT;
one of a source region and a drain region of the EL driver TFT is connected to the electric power source supply line, and the other is connected to the EL element;
a source region of the reset TFT is connected to the sensor electric power source line;
a drain region of the reset TFT is connected to a gate electrode of the buffer TFT and to the photodiode;
a drain region of the buffer TFT is connected to the sensor electric power source line;
one of a source region and a drain region of the selection TFT is connected to the sensor output wiring, and the other is connected to a source region of the buffer TFT;
a gate electrode of the selection TFT is connected to the gate signal line;
the polarity of the switching TFT and the selection TFT is the same;
light emitted from the EL element is reflected by a subject and irradiated to the photodiode; and
an image signal generated from the light irradiated to the photodiode is input to the sensor output wiring.
According to the present invention there is provided:
an adhesion type area sensor comprising a sensor portion, having a plurality of pixels, formed on a sensor substrate, characterized in that:
the plurality of pixels have a photodiode, an EL element, a switching TFT, an EL driver TFT, a reset TFT, a buffer TFT, a selection TFT; a source signal line; a gate signal line; an electric power source supply line for maintaining a constant electric potential; a reset gate signal line; a sensor gate signal line; a sensor output wiring connected to a constant electric current power supply; and a sensor electric power source line for maintaining a constant electric potential;
a gate electrode of the switching TFT is connected to the gate signal line;
one of a source region and a drain region of the switching TFT is connected to the source signal line, and the other is connected to a gate electrode of the EL driver TFT;
one of a source region and a drain region of the EL driver TFT is connected to the electric power source supply line, and the other is connected to the EL element;
a source region of the reset TFT is connected to the sensor electric power source line;
a drain region of the reset TFT is connected to a gate electrode of the buffer TFT and to the photodiode;
a drain region of the buffer TFT is connected to the sensor electric power source line;
one of a source region and a drain region of the selection TFT is connected to the sensor output wiring, and the other is connected to a source region of the buffer TFT;
a gate electrode of the selection TFT is connected to the gate signal line;
the reset TFT and the selection TFT are switched from an ON state to an OFF state, or from an OFF state to an ON state at the same time in accordance with the signal input to the reset gate signal line and the sensor gate signal line;
when one of the reset TFT and the selection TFT is in an ON state, the other is in an OFF state;
light emitted from the EL element is reflected by a subject and irradiated to the photodiode; and
an image signal generated from the light irradiated to the photodiode is input to the sensor output wiring.
According to the present invention there is provided;
an adhesion type area sensor comprising a sensor portion, having a plurality of pixels, formed on a substrate, characterized in that:
the plurality of pixels have a photodiode, an EL element, a switching TFT, an EL driver TFT, a reset TFT, a buffer TFT, a selection TFT; a source signal line; a gate signal line; an electric power source supply line for maintaining a constant electric potential; a reset gate signal line; a sensor gate signal line; a sensor output wiring connected to a constant electric current power supply; and a sensor electric power source line for maintaining a constant electric potential;
a gate electrode of the switching TFT is connected to the gate signal line;
one of a source region and a drain region of the switching TFT is connected to the source signal line, and the other is connected to a gate electrode of the EL driver TFT;
one of a source region and a drain region of the EL driver TFT is connected to the electric power source supply line, and the other is connected to the EL element;
a source region of the reset TFT is connected to the sensor electric power source line;
a drain region of the reset TFT is connected to a gate electrode of the buffer TFT and to the photodiode;
a drain region of the buffer TFT is connected to the sensor electric power source line;
one of a source region and a drain region of the selection TFT is connected to the sensor output wiring, and the other is connected to a source region of the buffer TFT;
a gate electrode of the selection TFT is connected to the sensor gate signal line;
the reset TFT and the selection TFT are switched from an ON state to an OFF state, or from an OFF state to an ON state at the same time in accordance with the signal input to the reset gate signal line and the sensor gate signal line;
when one of the reset TFT and the selection TFT is in an ON state, the other is in an OFF state;
light emitted from the EL element is reflected by a subject and irradiated to the photodiode; and
an image signal generated from the light irradiated to the photodiode is input to the sensor output wiring.
According to the present invention there is provided;
a display device comprising a sensor portion, having a plurality of pixels, formed on a substrate, characterized in that:
the plurality of pixels have a photodiode, an EL element, a switching TFT, an EL driver TFT, a reset TFT, a buffer TFT, and a selection TFT;
light emitted from the EL element is controlled in accordance with the switching TFT and the EL driver TFT; and
the sensor portion displays an image in accordance with the light emitted from the EL element; or the light emitted from the EL element is irradiated to the photodiode by being reflected by a subject, and an image signal is generated from the light irradiated to the photodiode in accordance with the photodiode, the reset TFT, the buffer TFT, and the selection TFT.
According to the present invention there is provided;
an adhesion type area sensor comprising a sensor portion, having a plurality of pixels, formed on a sensor substrate, characterized in that:
the plurality of pixels have a photodiode, an EL element, a switching TFT, an EL driver TFT, a reset TFT, a buffer TFT, a selection TFT; a source signal line; a gate signal line; an electric power source supply line for maintaining a constant electric potential; a reset gate signal line; a sensor gate signal line; a sensor output wiring connected to a constant electric current power supply; and a sensor electric power source line for maintaining a constant electric potential;
a gate electrode of the switching TFT is connected to the gate signal line;
one of a source region and a drain region of the switching TFT is connected to the source signal line, and the other is connected to a gate electrode of the EL driver TFT;
one of a source region and a drain region of the EL driver TFT is connected to the electric power source supply line, and the other is connected to the EL element;
a source region of the reset TFT is connected to the sensor electric power source line;
a drain region of the reset TFT is connected to a gate electrode of the buffer TFT and to the photodiode;
a drain region of the buffer TFT is connected to the sensor electric power source line;
one of a source region and a drain region of the selection TFT is connected to the sensor output wiring, and the other is connected to a source region of the buffer TFT;
a gate electrode of the selection TFT is connected to the sensor gate signal line;
light emitted from the EL element is controlled in accordance with the switching TFT and the EL driver TFT; and
the sensor portion displays an image in accordance with the light emitted from the EL element; or the light emitted from the EL element is irradiated to the photodiode by being reflected by a subject, and an image signal is generated from the light irradiated to the photodiode in accordance with the photodiode, the reset TFT, the buffer TFT, and the selection TFT.
According to the present invention there is provided;
an adhesion type area sensor comprising a sensor portion, having a plurality of pixels, formed on a sensor substrate, characterized in that:
the plurality of pixels have a photodiode, an EL element, a switching TFT, an EL driver TFT, a reset TFT, a buffer TFT, a selection TFT; a source signal line; a gate signal line; an electric power source supply line for maintaining a constant electric potential; a reset gate signal line; a sensor gate signal line; a sensor output wiring connected to a constant electric current power supply; and a sensor electric power source line for maintaining a constant electric potential;
a gate electrode of the switching TFT is connected to the gate signal line;
one of a source region and a drain region of the switching TFT is connected to the source signal line, and the other is connected to a gate electrode of the EL driver TFT;
one of a source region and a drain region of the EL driver TFT is connected to the electric power source supply line, and the other is connected to the EL element;
a source region of the reset TFT is connected to the sensor electric power source line;
a drain region of the reset TFT is connected to a gate electrode of the buffer TFT and to the photodiode;
a drain region of the buffer TFT is connected to the sensor electric power source line;
one of a source region and a drain region of the selection TFT is connected to the sensor output wiring, and the other is connected to a source region of the buffer TFT;
a gate electrode of the selection TFT is connected to the sensor gate signal line;
the reset TFT and the selection TFT are switched from an ON state to an OFF state, or from an OFF state to an ON state at the same time in accordance with the signal input to the reset gate signal line and the sensor gate signal line;
when one of the reset TFT and the selection TFT is in an ON state, the other is in an OFF state;
light emitted from the EL element is controlled in accordance with the switching TFT and the EL driver TFT; and
the sensor portion displays an image in accordance with the light emitted from the EL element; or the light emitted from the EL element is irradiated to the photodiode by being reflected by a subject, and an image signal is generated from the light irradiated to the photodiode in accordance with the photodiode, the reset TFT, the buffer TFT, and the selection TFT.
According to the present invention there is provided;
an adhesion type area sensor comprising a sensor portion, having a plurality of pixels, formed on a sensor substrate, characterized in that:
the plurality of pixels have a photodiode, an EL element, a switching TFT, an EL driver TFT, a reset TFT, a buffer TFT, a selection TFT; a source signal line; a gate signal line; an electric power source supply line for maintaining a constant electric potential; a reset gate signal line; a sensor gate signal line; a sensor output wiring connected to a constant electric current power supply; and a sensor electric power source line for maintaining a constant electric potential;
a gate electrode of the switching TFT is connected to the gate signal line;
one of a source region and a drain region of the switching TFT is connected to the source signal line, and the other is connected to a gate electrode of the EL driver TFT;
one of a source region and a drain region of the EL driver TFT is connected to the electric power source supply line, and the other is connected to the EL element;
a source region of the reset TFT is connected to the sensor electric power source line;
a drain region of the reset TFT is connected to a gate electrode of the buffer TFT and to the photodiode;
a drain region of the buffer TFT is connected to the sensor electric power source line;
one of a source region and a drain region of the selection TFT is connected to the sensor output wiring, and the other is connected to a source region of the buffer TFT;
a gate electrode of the selection TFT is connected to the sensor gate signal line;
the polarity of the switching TFT and the selection TFT are the same;
light emitted from the EL element is controlled in accordance with the switching TFT and the EL driver TFT; and
the sensor portion displays an image in accordance with the light emitted from the EL element; or the light emitted from the EL element is irradiated to the photodiode by being reflected by a subject, and an image signal is generated from the light irradiated to the photodiode in accordance with the photodiode, the reset TFT, the buffer TFT, and the selection TFT.
According to the present invention there is provided;
an adhesion type area sensor comprising a sensor portion, having a plurality of pixels, formed on a sensor substrate, characterized in that:
the plurality of pixels have a photodiode, an EL element, a switching TFT, an EL driver TFT, a reset TFT, a buffer TFT, a selection TFT; a source signal line; a gate signal line; an electric power source supply line for maintaining a constant electric potential; a reset gate signal line; a sensor gate signal line; a sensor output wiring connected to a constant electric current power supply; and a sensor electric power source line for maintaining a constant electric potential;
a gate electrode of the switching TFT is connected to the gate signal line;
one of a source region and a drain region of the switching TFT is connected to the source signal line, and the other is connected to a gate electrode of the EL driver TFT;
one of a source region and a drain region of the EL driver TFT is connected to the electric power source supply line, and the other is connected to the EL element;
a source region of the reset TFT is connected to the sensor electric power source line;
a drain region of the reset TFT is connected to a gate electrode of the buffer TFT and to the photodiode;
a drain region of the buffer TFT is connected to the sensor electric power source line;
one of a source region and a drain region of the selection TFT is connected to the sensor output wiring, and the other is connected to a source region of the buffer TFT;
a gate electrode of the selection TFT is connected to the sensor gate signal line;
the polarity of the switching TFT and the selection TFT are the same;
the reset TFT and the selection TFT are switched from an ON state to an OFF state, or from an OFF state to an ON state at the same time in accordance with the signal input to the reset gate signal line and the sensor gate signal line;
when one of the reset TFT and the selection TFT is in an ON state, the other is in an OFF state;
light emitted from the EL element is controlled in accordance with the switching TFT and the EL driver TFT; and
the sensor portion displays an image in accordance with the light emitted from the EL element; or the light emitted from the EL element is irradiated to the photodiode by being reflected by a subject, and an image signal is generated from the light irradiated to the photodiode in accordance with the photodiode, the reset TFT, the buffer TFT, and the selection TFT.
The EL element may have an anode, a cathode, and an EL layer formed between the anode and the cathode.
The EL driver TFT may be a p-channel TFT when the anode of the EL element is connected to a source region or a drain region of the EL driver TFT.
The EL driver TFT may be an n-channel TFT when the cathode of the EL element is connected to the source region or the drain region of the EL driver TFT.
The photodiode may have a cathode, an anode, and a photoelectric conversion layer formed between the cathode and the anode.
The reset TFT may be an n-channel TFT and the buffer TFT may be a p-channel TFT when the anode of the photodiode is connected to a drain region of the reset TFT.
The reset TFT may be a p-channel TFT and the buffer TFT may be an n-channel TFT when the cathode of the photodiode is connected to the drain region of the reset TFT.
The display device may have a touch pen and a touch panel.